CIRCULATING ALDOSTERONE CONCENTRATION RELATES TO RENIN SECRETION RATE

Objective: The renin-angiotensin-aldosterone system (RAAS) is one of the main long-term regulators of arterial blood pressure. Disturbances in the RAAS components can lead to hypertension, making them important screening markers to use when secondary forms of hypertension are suspected. In particular, the aldosterone-to-renin ratio (ARR) is used as a screening tool for primary aldosteronism. The purpose of this study is to examine the interplay between circulating arterial aldosterone, active plasma renin concentration (APRC), and the renin secretion rate (RSR). Design and method: We studied a total of 143 patients with resistant hypertension who underwent renal angiography with normal results. The study was limited to patients with essential hypertension and no evidence of secondary causes of hypertension. Medications were discontinued 3 weeks prior to the investigation and patients had a controlled sodium intake of 55 mmol/L for a week before the investigation. All patients underwent renal angiography with simultaneous measurements of active plasma renin concentration and aldosterone concentration in the right vein, left renal vein and aorta. Renin secretion rate was calculated for each side using the venoarterial APRC difference multiplied by renal plasma flow in the respective side. Results: Our study demonstrates a positive and significant correlation between circulating aldosterone and both right and total renin secretion rate (r=0.37, p=0.004, and r=0.37, p=0.004, respectively). Age showed an inverse correlation with right, left and total renin secretion rate (r-0.39 p=0.0032, r=-0.28 p=0.0335, and r=-0.39 p=0.0028, respectively). This resulted in an inverse correlation between age and APRC (r=-0.33, p=0.0004) and subsequently a positive correlation between age and ARR (r= 0.25 p=0.0095). Conclusions: Renin secretion rate appears to be the sole determinant of circulating aldosterone and is inversely correlated with age.